Automatic unstacker for veneer and other materials



April 15, 1969 BmDGES ET AL 3,438,623

AUTOMATIC UNSTACKER FOR VENEER AND OTHER MATERIALS Filed Feb 27, 1967 Sheet of 2 INVENTORS 3% 2. ROBERT L. BRIDGES BY EARL D. HASENM/YME zagg, m k ifi ww-w I N VEN TOR3 Sheet m EF ROBERT 1.. [SW/D653 EARL D. H/lSE/YlW/YKZE April 15, 1969 R. L. BRlDGEs ET AL AUTOMATIC UNSTACKER FOR VENEER AND OTHER MATERIALS Filed Feb. 27. 1967 United States Patent Office 3,438,623 AUTOMATIC UNSTACKER FOR VENEER AND OTHER MATERIALS Robert L. Bridges, Kelso, and Earl D. Hasenwinkle, Longview, Wash., assignors to Weyerhaeuser Company, Ta-

coma, Wash., a corporation of Washington Filed Feb. 27, 1967, Ser. No. 618,668 Int. Cl. B65h 3/06, /06

US. Cl. 271-39 4 Claims ABSTRACT OF THE DISCLOSURE Background of the invention In the manufacture of plywood and other laminated materials it has been a conventional practice to unstack veneer by hand for placement on a conveyor; however, with high-speed automated systems, manual unstacking of veneer is not practical or efficient. Although several means are known for unstacking planar materials, they are not readily adaptable to unstacking veneer layer by layer and transferring it to a conveyor because of the various sizes and uneven nature of the veneer. The use of friction belts, for example, to peel off the surface layer of a stack of veneer has not worked to any extent because, if sufficient pressure is applied between the belts and the veneer surface to drive the veneer from the pile, the downward pressure of the belts on the stack results in multiple feeding. The use of a gating device in conjunction with the friction belts to prevent multiple feeding is unworkable because of the unevenness of the veneer to be unstacked.

Summary This invention has for its primary purpose a method and means to unstack planar material and deliver it directly to a conveyor. Although this invention is applicable to unstacking of many different planar materials it is most useful in unstacking core veneer for automated plywood manufacture such as in conjunction with the wet-web production of plywood described in US. Patent No. 3,247,042. The machine of this invention allows unstacking of material with a minimum of multiple feeding by use of driving discs having high horizontal friction with the material but with minimum lvertical pressure.

Brief description of the drawings An embodiment of the equipment is illustrated in the drawings wherein:

FIGURE 1 is an elevation of the feed end of the machine,

FIGURE 2 is an elevation of the discharge end of the machine, and

FIGURE 3 is a sectional view taken along broken section line 3-3 of FIGURE 1.

Detailed description of the drawings Referring to the drawings in detail, 1 designates the overall frame of the machine. A pair of opposed rolls 2 are attached to the frame as shown and are driven by suitable means (not shown). The stack of planar material 3, which may be veneer or other material, is supported on 3,438,623 Patented Apr. 15, 1969 a conventional X-frame lift table 4 having suitable powered means to raise and lower the table. A photoelectric cell 5 operatively connected to the powered means of the lift table, is positioned adjacent the lift table as shown. As long as the light beam is unbroken the lift table raises the stack of veneer. Positioned above the lift table and the stack of material to be transferred are a plurality of arms 6 mounted on a main support shaft 7. Clutches 8, either magnetic or other, are mounted on the arms 6 either above or below the arms. On the ends of the arms overhanging the material to be transferred are attached driving discs 27. Sprockets 11 are mounted within the arms 6 and chains 12 connect the sprockets 11 and 13. A motor 14, or other suitable means, drives the main support shaft 7 which, in turn, is connected. to the clutches 8 by chains and sprockets 15, 16, and 17, and shafts 9. The outputs of the clutches on which sprockets 18 are mounted are connected to sprockets 20 by chains 19. On the ends of arms 6 opposite the driving discs 27, counterbalances 21 may be mounted as shown to control the downward weight of the arms on the material to be transferred. Above each of the arms and attached to the frame 1 are a series of rheostats 22 having ladder chain sprockets 23 attached to each of the shafts of the rheostats. Chains 24, attached to the arms 6 and over sprockets 23, have weights 25 attached to their free end. The rheostats are electrically connected to the clutches for varying the voltage delivered to the clutches. A conventional conveyor 26 is situated at right angles to the unstacker for further transferring the separate pieces of core to equipment (not shown). The drive discs 27 depicted in the drawing are a series of serrated discs, typically saw blades, however, any configuration disc capable of exerting a high horizontal force on the top layer of material to be transferred may be used.

In actual operation a stack of core is transferred onto the X-lift and raised to the drive discs. The photocell situated adjacent to the lift controls the level of the veneer. The drive discs engage the veneer and move it a few inches into the opposed rotating rolls which in turn rapidly transfer the pieces onto the conveyor. The speed ratio of the rolls to the driving discs, for example, may range from 4:1 to 8:1.

In order to prevent multiple feeding of the material it is essential that a significantly high force be exerted on the surface layer of material in a horizontal direction and that a minimum of vertical pressure be exerted on the stack of material. This is achieved by (1) control of the height to which the stack of material is raised by the lift table on which it is supported, (2) the weight of the driving discs resting on the surface layer of material, and (3) the driving force exerted by the discs on the surface layer of material. The height of the stack of material is controlled by the photoelectric cell. The weight of the driving discs on the stack of material is controlled and varied by the counterweight attached to the ends of the arms opposite the driving discs. The driving force applied to the driving discs through the clutches is controlled and may be varied through the rheostats. As the discs on the arms are lowered, the chain and sprocket linkages over the rheostats turn the rheostats and increase the resistance in the clutch electrical circuits which, in turn, produce a lower voltage to the clutches and results in a lower driving force at the driving discs. As the arms are moved upward the process is reversed and an increasing driving force results until sufficient force is attained to move the surface layer of material into the opposed rolls.

This machine is particularly well adapted to unstacking and transferring core veneer which is normally clipped in varying widths and standard lengths or uniform widths and standard lengths. The former is usually designated random core and is stacked into a roughly square package with the outside edges of the load uniform and the inner portions varying and often interlaced with other core veneer. The latter is designated tailor made and normally consists of two uniform piles stacked side by side to form roughly a square package. The machine of this invention is able to unstack either random or tailor made core of commonly used thicknesses.

The apparatus of this invention can also be operated without the rheostat mechanism as described to control the force delivered to the driving disc. In operating the machine in this manner the force necessary to transfer the veneer to the conveyor is controlled by the level which the veneer is raised and the downward Weight of the driving discs on the surface layer of veneer. The driving force transmitted to the driving discs through the clutches in this instance remains constant.

In summary, the method and means of this invention provide a relatively efiicient and inexpensive way of transferring material, particularly core veneer, directly to a conveyor at speeds compatible with the machines use in conjunction with automated plywood systems.

Having described my invention, what I claim is:

1. A machine for unstacking and transferring a stack of wood veneer directly to a conveyor which comprises in combination:

(a) a lift table supporting a stack having a surface layer of veneer to be transferred,

(b) powered means operatively connected to the lift table to raise and lower the table surface supporting the stack of veneer,

() height sensing means positioned adjacent to and operatively connected with the lift table on which the veneer is stacked so as to control the level of the veneer,

((1) feed means positioned adjacent to and engageable with the surface layer of the veneer comprising:

(1) a shaft normal to the direction of movement of the veneer,

(2) a plurality of arm members mounted rotatably on the shaft parallel to the direction in which the veneer is to be moved, and

(3) delivery means for engaging the veneer rotatably mounted on the ends of the arms overhanging the veneer,

(e) magnetic clutches operatively connected to the de livery means,

(f) power means operatively connected to the magnetic clutches to drive the clutches, and

(g) means operatively connected to the clutches for varying the power output of each of the clutches in response to the upward and downward movement of the respective arm members.

2. A machine according to claim 1 wherein the delivery means comprises a series of serrated discs.

3. A machine for unstacking and transferring a stack of planar material directly to a conveyor which comprises:

(a) means for supporting a stack of material having a surface layer of material to be transferred,

(b) circular feeding discs mounted for movement relative to the stack surface and positioned normal to and engageable with the surface layer of the stack of material,

(c) means for moving the stack surface relative to the feed means, and

(d) drive means operatively connected to the circular feeding discs comprising (1) a series of clutches operatively connected to each of the circular feeding discs,

(2) power means operatively connected to the clutches to drive the clutches, and

(3) means for varying the power output of the clutches to the respective feeding discs to control the driving force applied to each of the discs, the power output of the clutches increasing on movement of the feeding discs in an upward direction and decreasing on movement of the feeding discs in a downward direction.

4. A machine according to claim 3 wherein the means for varying the power output of the clutches comprises rheostats operatively connected to each of the clutches and arm members.

References Cited UNITED STATES PATENTS 2,571,942 10/1951 Properzi 271-36 2,819,078 1/ 1958 Durand 27139 3,021,136 2/1962 Fox 271-36 3,062,534 11/1962 Benson et a1 27136 FOREIGN PATENTS 551,629 10/1956 Belgium.

RICHARD E. AEGERTER, Primary Examiner". 

